The IMAGE format as used by some commands in earlier versions of KAPPA is a simple HDS structure, comprising a floating-point data array, a character title, and the maximum and minimum data values. It is variant of the original Wright-Giddings IMAGE structure. There are others is use that contain more items. An example structure is shown schematically below using the HDSTRACEnotation; see the NDF format.
HORSEHEAD <IMAGE> DATA_ARRAY(384,512) <_REAL> 100.5,102.6,110.1,109.8,105.3,107.6, ... 123.1,117.3,119,120.5,127.3,108.4 TITLE <_CHAR*72> 'KAPPA - Flip' DATA_MIN <_REAL> 28.513 DATA_MAX <_REAL> 255.94 End of Trace.
The DATA_ARRAY may have up to seven dimensions. IMAGE structures are associated with parameters like INPIC and OUTPIC. The TITLE object of new IMAGE structures takes the value of the Parameter OTITLE. DATA_MIN and DATA_MAX are now ignored.
The IMAGE format is not too dissimilar from a primitive NDF
with no extensions. Indeed if it did not have DATA_MAX and DATA_MIN
it would be a bona fide NDF. Thus applications that handle the
IMAGE format can follow the rules of SGP/38 and
process it like an NDF. In effect this means that all extensions are
propagated to output files, and a quality array is propagated where
the processing does not invalidate its values. IMAGE applications
also handle most simple NDFs correctly (those where the data
array is an array of numbers at the second level of the hierarchical
structure). This similarity in formats enables NDF and IMAGE
applications to work in co-operation, and so the conversion within
KAPPA was undertaken piecemeal over several years.
Note that the primitive
variant is no longer the norm for NDFs, since for example, it does not
support origin information.
KAPPA --- Kernel Application Package